postgresql - DATE Between 的慢速选择查询

Question

我搜索了一下我的问题，但找不到解决方案。

我在 x86_64-unknown-linux-gnu 上运行 PostgreSQL 9.2.4，由 gcc (Debian 4.7.2-5) 4.7.2, 64-bit 编译，我的查询非常简单.

EXPLAIN (ANALYZE) SELECT CUSTOMER, PRICE, BUYDATE FROM dbo.Invoice WHERE CUSTOMER = 11111111 AND BUYDATE BETWEEN '2012-11-01' AND '2013-10-31';

输出:

                                                                       QUERY PLAN
-----------------------------------------------------------------------------------------------------------------------------------
 Bitmap Heap Scan on Invoice  (cost=88193.54..152981.03 rows=20699 width=14) (actual time=987.205..987.242 rows=36 loops=1)
   Recheck Cond: ((CUSTOMER = 11111111) AND (BUYDATE >= '2012-11-01'::date) AND (BUYDATE <= '2013-10-31'::date))
   ->  BitmapAnd  (cost=88193.54..88193.54 rows=20699 width=0) (actual time=987.189..987.189 rows=0 loops=1)
         ->  Bitmap Index Scan on ix_Invoice  (cost=0.00..1375.69 rows=74375 width=0) (actual time=0.043..0.043 rows=40 loops=1)
               Index Cond: (CUSTOMER = 11111111)
         ->  Bitmap Index Scan on ix_Invoice3  (cost=0.00..86807.24 rows=4139736 width=0) (actual time=986.562..986.562 rows=4153999 loops=1)
               Index Cond: ((BUYDATE >= '2012-11-01'::date) AND (BUYDATE <= '2013-10-31'::date))
 Total runtime: 987.294 ms
(8 rows)

表结构:

      Column      |           Type            | Modifiers | Storage  | Stats target | Description
-----------------+---------------------------+-----------+----------+--------------+-------------
 profitcenter    | character varying(5)      | not null  | extended |              |
 invoicenumber   | character varying(10)     | not null  | extended |              |
 invoiceposition | character varying(6)      | not null  | extended |              |
 buydate         | date                      | not null  | plain    |              |
 customer        | integer                   |           | plain    |              |
 nettowert       | numeric(18,2)             |           | main     |              |
Indexes:
    "filialbons_key" PRIMARY KEY, btree (profitcenter, invoicenumber, invoiceposition, buydate)
    "ix_Invoice" btree (customer)
    "ix_Invoice2" btree (invoicenumber)
    "ix_Invoice3" btree (buydate)
    "ix_Invoice4" btree (articlenumber)
Has OIDs: no

查询的示例输出:

customer | price | buydate
--------------+-----------+----
 11111111 |  8.32 | 2013-02-06
 11111111 |  5.82 | 2013-02-06
 11111111 | 16.64 | 2013-02-06

我在 MSSQL 2010 上运行了相同的查询？将日期列表示为 varchar()，速度要快得多。

谢谢你的帮助

Answer 1

1. 在 (customer, buydate) 查询上使用索引应该工作得更快。

2. 您可以尝试通过收集更多的统计数据来帮助计划者选择更好的计划:

   ALTER TABLE 发票 ALTER COLUMN 客户 SET STATISTICS 1000;
   ALTER TABLE 发票 ALTER COLUMN buydate SET STATISTICS 1000;
   分析发票；